|YOU'VE FORGOTTEN YOUR PURPOSE!
Aku City was a city that was the main location in the future in several episodes.
Aku at some point has established this city some time after he conquered much of the world. Because of mountains of tributes that flowed in from around the world in name of Aku, the city has became the wealthiest settlement on Earth. Aku centralized the bulk of his military industrial complex within the city, also making it a technological and commercial hub. People from all over the world flocked to the city in search of employment and residency, having to completely submit to Aku's rule. Because of this, the city was not only the world's political capital akin to the United Nations, but also its largest population center. However, it quickly became a hotbed for a resistance movement against Aku. Aku would rectify this issue by mobilizing his scientific advisors to develop automated drones to hunt down and eliminate agitators. It took time, but eventually the scientists produced the X-Series which were incredibly effective at purging subversive cells, causing severe collateral damage to the city. Eventually, all but one of the X-Series were destroyed and the resistance was either broken or driven out of the city. Absent of oppositions and impatient with the extent of his conquests, Aku commissioned his city as a spaceport, sending his forces out into interstellar expeditions to raid foreign planets of their resources and people. Over the next millennia, the City of Aku was the predominant entry point on Earth for the masses of natural commerce and migration as well as forceful tribute and enslavement. Humans quickly found themselves as a minority among many species of aliens arriving on Earth and robots being built. In this time the City of Aku rapidly expanded into a super metropolis.
The city was presumably erased from existence after the destruction of the past Aku.